In order to investigate for peaks at 101 Hz, 107 Hz, 157 Hz (41824) today we performed tappings in the area between IB and SIB2, including various spots along the B2 and RFC minilinks. We did it first with only RFC locked and ITF in recombined (INDEX = 82), then we repeated with SSFS locked (ITF index = 92). Figures 1 and 2 show the tapping locations in the first and second round respectively. We used the electronic hammer as a tool (but not acquired) and at some point (indicated below) we connected channel ENV_IB_BD_ACC_Z (usually connected to the PCB accelerometer on the W-flange beam dump) to one small accelerometer which we sticked in a few places (described below) and finally we left it sticked on the RFC flange (IB side) in horizontal direction.
Here the detailed time list:
***** tapping test in SIB2 room 22/06/2018 **************** signals: Sc_MC_RFC_Err_Post (error signal for the IMC length lock, which in our case was using B4 (CARM error signal) and not RFC) **************************************************************************************************************************************************************************************** ****** recombined mode (PR misaligned, arms locked, carm to MC we use RFC error signal for the correction to the mode cleaner) **** GPS given in LOCAL TIME reference: 09:13:00 * is where we see well the 101Hz peak excited 1) 09:22:05 --> 09:23:10 B2 minilink SIB2 side 2) 09:23:31 --> 09:24:15 B2 minilink middle 3) 09:24:50 --> 09:25:35 B2 minilink INJ tower side 4) 09:25:54 --> 09:26:27 5) 09:27:12 --> 09:27:34 6) 09:29:38 --> 09:30:04 * flange 7) 09:31:13 --> 09:32:00 * in the middle of the REF minilink 8) 09:32:27 --> 09:32:59 * 9) 09:33:15 --> 09:34:02 * 10) 09:35:27 --> 09:36:05 lateral flange IB 11) 09:40:30 --> 09:40:48 small flange 12) 09:41:17 --> 09:41:31 13) 09:41:32 --> 09:41:47 14) 09:42:14 --> 09:42:21 15) 09:42:35 --> 09:42:43 16) 09:42:50 --> 09:43:58 17) 09:43:50 --> 09:43:58 18) 09:44:04 --> 09:44:15 19) 09:44:30 --> ? * 20) 09:44:45 --> 09:44:58 * 21) 09:45:41 --> 09:45:55 22) 09:54:03 --> 09:54:20 from inside SIB2, close to the window --> nothing 23) 09:54:48 --> 09:55:01 same as 23 *** we put the accelerometer (ENV_IB_BD_ACC_Z) in the vertical direction on the RFC pipe (in the middle). 24) 10:31:34 --> 10:32:42 tapping on the minilink **************************************************************************************************************************************************************************************** ******** measurement with SSFS engaged *********** new reference: 10:41:00 Signals: - Sc_MC_RFC_Err_Post (even if the RFC is unlocked it is still the signal to look at) - ENV_IB_BD_ACC_X on the big flange, north side - ENV_IB_BD_ACC_Z on hte RFC minilink, along the beam direction 1) 10:43:24 --> 10:44:01 on the REF cavity minilink, close to INJ tower, along the beam direction 2) unlock 3) 10:51:23 --> 10:52:03 " " , along the vertical direction 4) 10:52:14 --> 10:52:39 on the B2 cavity minilink, close to INJ tower, along the beam direction 5) 10:52:51 --> 10:52:07 6) 10:53:17 --> 10:53:40 on the beam dump, along the beam direction 7) 10:53:52 --> 10:54:09 at the center of the flange 8) 10:54:19 --> 10:54:32 close to RFC pipe * 9) 10:54:40 --> 10:54:49 closer to RFC pipe * 10) 11:01:28 --> 11:01:50 RFC minilink, close to INJ tower, along the beam direction 11) 11:02:50 --> 11:02:25 RFC minilink, in the middle, along the beam direction 12) 11:02:40 --> 11:03:08 RFC minilink, close to INJ tower, in the vertical direction 13) 11:03:22 --> 11:03:45 RFC minilinj, close to SIB2, on the beam direction 14) 11:03:54 --> 11:04:20 as 10 15) 11:08:35 --> 11:08:55 16) 11:10:24 --> 11:10:32 tapping on the flange, next to RFC minilink, in the direction of the beam 17) 11:11:30 --> 11:11:40 18) 11:15:52 --> 11:16:05 19) 11:16:25 --> 11:16:45 side of the flange, next to the rfc minilink 20) 11:29:24 --> 11:29:59 on the side of the flange, transverse direction
